Regulating devices for the flow of fuel in internal combustion engines

ABSTRACT

The device comprises a centrifugal regulator, a first element mechanically actuated by the regulator, a second element actuating a regulating member for the flow per revolution of the pump, and linking means between the two elements including a hydraulic servo device. The latter is of the follower type and comprises a pilot slide valve constituting the first element and a jack provided with a differential piston constituting the second element. The slide valves and differential piston define a variable by-pass. The regulating member is constituted by first and second levers pivoted on axles which are connected to one another by a hydraulic time-delay. The device is especially useful for controlling the flow of large injection pumps.

United States Patent Vuaille [54] REGULATING DEVICES FOR THE FLOW OF FUEL IN INTERNAL COMBUSTION ENGINES [72] Inventor: Andre Vuaille, Lyon, France [73] Assignee: Societe lndustrielle Generale de Mecanique Appliquee S.I.G.M.A., Venissieux, France I 221 Filed: Dec. 30, 1970 211 Appl.No.: 102,604

[30] Foreign Application Priority Data Dec. 3i, I969 France ..6945752 [52] U.S.Cl. ..123/140 R,l23/l40 PG [51] Int. Cl. ..F02d l/04, F02d 31/00 [58] Field of Search.....l23/l40 R, 140 PO, 140 MC, 123/140 [56] References Cited UNITED STATES PATENTS 3,145,624 8/1964 Parks et al. ..123/140 R 3,499,426 3/1970 Bailey ..123/140 R Oct. 17, 1972 FOREIGN PATENTS OR APPLICATIONS 166,312 12/1933 Switzerland ..l23/14OR 822,343 12/1937 France ..l23/l40R Primary Examiner-Laurence M. Goodridge Assistant Examiner-Cort Flint Attorney-Waters, Roditi, Schwartz & Nissen 571 ABSTRACT The device comprises a centrifugal regulator, a first element mechanically actuated by the regulator, a second element actuating a regulating member for the flow per revolution of the pump, and linking means between the two elements including a hydraulic servo device. The latter is of the follower type and comprises a pilot slide valve constituting the first element and a jack provided with a differential piston constituting the second element. The slide valves and differential piston define a variable by-pass. The regulating member is constituted by first and second levers pivoted on axles which are connected to one another by a hydraulic time-delay. The device is especially useful for controlling the flow of large injection pumps.

13 Claims, 15Drawing Figures REGULATING DEVICES FOR THE FLOW OF FUEL IN INTERNAL COMBUSTION ENGINES The invention relates to a regulating device for the flow of fuel per revolution for injection pumps for internal combustion engines of the type comprising:

a centrifugal regulator adapted to be driven by the engine;

a first element mechanically actuated by the centrifugal regulator, through a lever;

and a second element controlling a regulating member for the flow per revolution of the pump to which it is mechanically linked, the said element being adapted to be displaced along parallel or common axes;

control means of the displacement of the second element from those of the first element comprising a hydraulic servo device using a fluid under pressure;

regulating means enabling adjustment of the variations in speed of rotation of the engine as a function of the load on the latter, comprising a second lever parallel to the preceding one, adapted to act on the servo device according to the displacements of the regulating member for flow per revolution.

The invention relates more particularly, because it is in this case that this application seems to have the most advantage, but not exclusively, among these fuel flow regulating devices, to those for large injection pumps which necessitate considerable energy for the actuating of the adjustment member for the flow per revolution.

It has already been proposed to use hydraulic servo devices to ensure linkage between the abovesaid first and second elements so as to amplify the actuating force given by the centrifugal regulator. Such devices are generally complicated and have considerable inertra.

It is a particular object of the invention to render the abovesaid regulating devices such that they respond to the various exigencies of practice better than hitherto and especially such that their bulk is reduced and that they enable better fidelity and precision of regulation to be obtained, by reduction of the inertia of the servo device.

According to the invention, a regulating device for the flow of fuel per revolution for injection pumps of internal injection engines of the type previously defined, is characterized by the fact that, on one hand, the hydraulic servo device is of the follower type and comprises a pilot slide valve constituting the abovesaid first element and a differential piston constituting abovesaid second element, the abovesaid slide valves and differential piston being adapted to define a varia ble by-pass cross-section dependent on their relative positions and to establish a load loss which .actuates the displacements of the said differential piston and, hence of the regulating member of flow per revolution of the pump and that, on the other hand, the first lever and the second lever are, respectively, articulated in their median part on an axle adapted to be displaced in the direction parallel to the axes of the abovesaid pilot slide valves and differential piston, the axles of the two levers being connected to one another through a hydraulic delay, the first lever being linked, at each of its ends, respectively, to the pilot slide and to an active member of the centrifugal regulator adapted to slide along the axis of the latter, the second lever being articulated, at one of its ends on a pivot fixed in the direction of the axis of the abovesaid slide valve, but

adjustable in a direction at right :angles to the axis of this slide valve and at its other end, being articulated on a regulating member for the flow per revolution of the pump.

Preferably, the pilot slide valve :is adapted to slide in a bore provided in the differential piston and to be guided by the latter, and includes a longitudinal channel opening inside said bore through at least one lateral orifice which cooperates with the surface of the said bore of the differential piston to define the above-said cross section of variable bypass.

The invention consists, apart from the features mentioned above, of certain other features which are preferably used at the same time and which will be more explicitly considered below with respect to the embodiments of the invention which will not be described with reference to the accompanying drawings, but which are given purely by way of non- Iimiting illustration. In these drawings:

FIG. 1 shows a section along the line I-I, of FIG. 3, of a regulating device according to the invention;

FIG. 2 shows a section along the line II-II of FIG. 3 of the regulating device;

FIG. 3 is a section along the line III- III of FIG. 1;

FIG. 4 is a section along the line llV-IV of FIG. 2;

FIG. 5 shows, similarly to FIG. 1, but partially, a regulating device with a flow stop adjustable in operation;

FIG. 6 shows, similarly to FIG. 5 a regulating device with two stop positions;

FIG. 7 shows, similarly to FIG. 4, but partially, a regulating device with an electric control for the arrest of the injection;

FIG. 8 is a diagram showing possible variations in speed of the rotation of an engine as a function of the torque supplied by the latter;

FIGS. 9 to 13 illustrate diagrammatically the operation of the regulating device in the case of nil statism;

FIG. 14 is a diagram illustrating the operation of the device in the case of positive statism; and

FIG. 15 lastly, is a simplified diagram corresponding to negative statism.

Referring to FIGS. 1 and 2, itis seen that the regulating device 1a comprises a centrifugal regulator 2a, adapted to be rotated by the shaft 3a of an engine (not shown) or by the cam shaft of an injection pump. This engine is supplied with fuel by an injection pump in line (not shown) of which the flow pezr revolution is regulated by the regulating device la.

The centrifugal regulator 2a comprises weights 4a, driven in rotation and which, under the action of the centrifugal force, can pivot around axles 5a.

Arms 6a, rigidly fixed to the weights 4a extend radially towards the axis of the regulator 20. The arms 6a bear, at their end remote from the weights 4a, fingers 7a. It is quite clear that the centrifugal regulator could be of a different type from the w'eight" type considered. There could, for example, be used a centrifugal regulator with single or double balls and inclined plates, such as that described in Applicants French Pat. No. 1,149,709.

Fingers 7a exert, on a pusher 8a, an axial force depending on the centrifugal force which acts on the weights 4a. The pusher 8a, in the form of a cylindrical sleeve, is rotated by friction on the shaft 30 and can slide along the geometrical axis of this shaft.

' The pusher 8a transmits the axial force which it receives from an active member or sleeve 9a which can be axially displaced against the action of elastic return means 10a. The sleeve 9a is prevented from turning and, through this fact, a ball race 11a is provided between the pusher 8a and the sleeve 9a. The latter bears a partly spherical universal joint 12a (FIGS. 3 and 4).

The elastic means 10a are advantageously constituted by one or several helical springs. The one or more said springs are compressed between the sleeve 9a and a cup 130.

The axial position of the cup 13a is controlled by the toothed sector 16a (FIG. 2). The latter meshes with teeth borne by a sleeve 47, on its outer surface. The sleeve 47 includes an internal threading with which an external threading borne by the cup 13a cooperates. The axial position of the latter can hence be adjusted in two manners:

either by displacement of the assembly of the sleeve 47 and of the cup 13a by means of the toothed sector 160,

or by rotation and concomitant longitudinal displacement of the cup 13a with respect to the sleeve 47 which is immobilized in rotation.

The placing in rotation of the cup 13a is obtained by means of a shaft 48 which can drive the said cup. This shaft 48 is put in motion either by a motor reducer 49 or by a manually controlled wheel (not shown). Cup 13a is mounted freely in translation on the shaft 48.

The stops 18a and 19a limit the rotation of the axle 17a and of the toothed sector 16a appearing in FIG. 4. The cam 20a, connected in rotation with the axis 17a is provided to cooperate with the screws 18a, 19a respectively at the maximal speed and at idling speed.

These two speeds can be adjusted due to the abovesaid screws.

The regulating device 1a comprises a first element 22a and a second element 32a belonging to a hydraulic servo device.

The mechanical control of the element 22a, constituted by a pilot slide valve, is assured by a lever 23a capable of turning around a median axis 24a at right angles to the axis of the pilot slide valve 22a.

As seen in FIG. 4, the lever 23a, which ensures mechanical linkage between the universal joint 12a and the first element or pilot slide valve 22a; has a double elbow, one of its ends being situated in a plane different from that of its other end.

The lever 23a is provided at one end with a finger 25a on which is mounted a roller 25b. This roller 25b is held in contact with the pilot slide valve- 22a by the spring 27a which is hooked on one hand on the finger 25a, on the other hand at the end of the pilot slide valve 22a remote from the finger 25a. The spring 27a is housed in a longitudinal channel a provided with the slide valve 22a.

The control of the slide valve 22a, by the lever 23a, is positive in the sense (FIG. 1) that is to say in the sense of reduction of flow per revolution and is effected by means of the spring 27a in the contrary sense, that is to say in the sense The axle 24a, on which the lever 23a is mounted, can be displaced with respect to the casing of the regulating device 1a, parallel to the axis of the slide valve 22a.

The element 22a is displaced from an axis parallel to that of the regulator 2a.

The spring 270 has a stiffness less than that of the elastic return means 10a.

A lever 28a, called stop lever and mounted on an axle of rotation at right angles to the axis of the slide valve 22a, enables positive control of the said slide valve to annul the flow of the injection pipe. This annulment of flow is obtained by displacing the lever 28a (in FIG. 1) towards the left.

The slide valve 22a, when inactive, is supported against a stop screw 29a enabling adjustment of the supercharge flow, that is to say of the maximum flow per revolution, involved especially at the time of starting the engine.

The regulating device comprises also the second element 32a controlling the regulating member 330 for the flow per revolution.

The member 33a is constituted by a rack displaced parallel to the axis of regulator 2a.

The second element 32a is constituted by a differential piston, comprising externally two coaxial cylindrical parts, one of large diameter, the other of smaller diameter, displaced in a cylinder 34a forming,-

with the piston, a jack. In the following, the reference 32a will be used to denote the differential piston. The

cylinder 34a comprises two coaxial bores of different diameters and equal respectively to those of the two outer parts of the differential piston 32a.

The latter has the shape of a sleeve comprising a central bore adapted to receive and to guide the slide valve 22a and can come, into abutment against a shoulder borne by the regulating member of the flow or rack 330 so as to control positively the displacements of this rack in the sense of reductions of flow per revolution, the sense denoted (FIG. 1) by an arrow surmounted by the sign In the contrary sense, that is to say in the sense, to which corresponds an increase in the flow per revolution, the piston 32a is elastically linked to the rack 33a by a spring 35a compressed between a stop provided at one end of the said rack and a shoulder, provided in the bore of the piston. A radial play is provided between the said shoulder and the end of the rack 33a. The spring 33a, in combination with this radical play, ensures self-centering of the rack 33a and of the piston 32a.

The cylinder 34a is closed, in sealed manner, by a cap 36a, displaceable in translation in a plane at right angles to the axis of the slide valve 22a and constituting the bottom of the cylinder on the side of the slide valve 22a. This mobility of the cap 36a in directions at right angles to the axis of the slide valve 22a results in the latter being guided solely by the bore of the piston 32a. The guidance of the slide valve 22a is excellent.

The part of large diameter of the piston 32a divides the cylinder 34a into two chambers 38a and 39a. The chamber 38a is comprised between the portion of large diameter of the piston 32a and the cap 36a and has a cross section of which the area is equal to 28.

The chamber 39a is situated on the opposite side of the cap 36a with respect to the part of large diameter of the piston 32a. This chamber 39a has a cross-section in the shape of a circular crown and of which the area is equal to S, that is to say equal to one-half of the area of the cross section of the chamber 38a.

An inlet pipe 40a (FIG. 1) for liquid under pressure opens into the chamber 39a.

The liquid under pressure can pass from the chamber 39a to the chamber 38a due to a passage 41a provided in the part of large diameter of the differential piston 32a.

The channel 30a places the chamber 38a in communication with the zone A of the casing where the relative pressure of the fluid is slight or nil, since this zone is connected by an exhaust pipe 44a (FIG. 2) to a-reservoir (not shown) placed at atmospheric pressure.

U The pilot slide valve 22a comprises a peripheral groove 50 communicating with the longitudinal channel 30a, through radial holes 51.

The longitudinal position of this groove 50 is such that, when the slide valve 22a comes into abutment against the piston 32a, the said groove is covered and closed by the cylindrical surface and the bore ofthe piston 32a. The chamber 380 is then isolated from the zone A of the casing at relatively slight or nil pressure. From this position, a slight relative displacement of the slide valve and of the piston, in a suitable sense, suffices for the groove 50 to be partly uncovered. The variable by-pass section between the chamber 38a and the zone A of the casing at relatively slight or nil pressure is hence determined by the cooperation of the latter opening, the groove 50, with a lateral surface, that is to say the cylindrical surface of the bore of the piston 32a.

The regulating device la comprises in addition regulating means, enabling adjustment of variations of the speed of rotation of the engine as a function of its load, comprising a second lever 52 (FIG. 1) substantially parallel to the first lever 23a.

This second lever 52 is articulated at one of its ends on a pivot 53 immobile, in the longitudinal direction, that is to say in the direction of the axis of the regulator 2a, with respect to the casing of the device la.

The pivot 53 is constituted by a finger rigidly fixed to a nut 54 (FIGS. 3 and 4) screwed on a threaded rod 55 manually controlled by a knob 56 (FIGS. 1, 2 and 4).

The threaded rod 55 is mounted on the casing of the regulating device la so as to be freely rotatable. The said rod 55 extends in a direction at right angles to that of the axis of the regulator 2a and to that of the axis of the regulating rack 53a.

The pivot 53 is engaged in a rectangular slot 57 provided in the lever 52 and extending in the direction of the large dimension of this lever (FIG. 1

The cooperation of a groove 54b (FIG. 3), arranged in the casing of the regulating device la, with a tab 54a, rigidly fixed to the nut 54, prevents the latter and the pivot 53 from turning when the threaded rod 55 is placed in rotation. The rotation of the rod 55 hence causes the displacement of the nut 54 and of the pivot 53 along the axis of the said rod. Regulation of the transverse position of the pivot 53 is thus possible.

The lever 52 is mounted freely in rotation, in its middle portion, on an axle 58 which can be displaced with respect to the casing of the device 51a.

The axle 58 is parallel to the axle 24a and situated at the same distance as the latter from the axis of the rack 33a.

At its end opposite the slot 57, the lever 52 is linked in translation with the rack 33a. The latter bears a pin 59 engaged in the slot 60 provided in the said lever 52 (FIG. 1).

The ends of each of the levers 23a and 52 are substantially situated at the apices of a parallelogram of whichtwo sides are constituted by the said levers and of which the two other sides are parallel to the axis of the rack 33a.

The axle 58 is linked to the axle 24a by a hydraulic delay 61 (FIG. 1).

The hydraulic delay 61 comprises a compensating piston 62 (FIGS. 9 to 12) adapted to slide in the bore 63 of a cylinder. It will be noted that the portion of the piston 62 situated in the bore 63 has a median zone of larger diameter and equal to the diameter of the bore 63 which defines a chamber 63a inside the bore 63.

The piston 62 comprises a rod which extends from the side of the lever 23a and which ends by a yoke bearing the axle 24a of the lever 23a (FIG. 1).

The compensating piston 62 comprises also a bore 64 which opens towards the lever 52. The axle 58 of the lever 52 is borne by a rod 65 coaxial to the piston 62 and which extends in the bore 64 of the said piston. The part of this rod 65 situated in the bore 64 bears two cups 66 and 67 between which a spring 68 is compressed. This spring 68 has a tendency to separate the cups 66 and 67 from one another and to push them back respectively against a shoulder 69 borne by the rod 65 and against a stop ring 70 anchored at the ends of the said rod 65 which is situated inside the bore 64. The latter comprises a shoulder 71 (FIGS. 9, 10) adapted to cooperate with the cup 67. A stop ring 72 (FIG. 1) is provided at the end of the bore 64 turned towards the lever 52, the said stop ring being anchored inthe piston 62 and being adapted to cooperate with the cup 66.

It will be noted that the axles'58 and 24a must remain parallel. It is hence necessary that the piston 62 be prevented from turning and for this there is provided a finger 73 (FIG. I), mounted in the cylinder surrounding the piston; this finger 73 cooperates with a longitudinal groove 74 provided on the outer surface of the piston 62.

In being displaced, the piston 62 causes variations in volume in the chamber 63a. This chamber is filled with liquid and communicates with the .zone A of the casing, where the relative pressure of liquid is low or nil, through a channel 75 (FIGS. 1, 3, 9 to 12) of which the cross-section of the passage can be adjusted by a needle screw 76. When the piston 62 is displaced towards the left of FIGS. 9 to 12, the volume of the chamber 62a diminishes and a quantity of liquid, corresponding to this reduction in volume, is recirculated into the zone A of the casing, through the channel 75.

For a displacement of the piston 62 in the opposite sense, that is to say towards the right of FIGS. 9 to 12, the volume of the chamber 63a increases and a quanti ty of liquid, corresponding to this increase in volume, is aspirated from the zone A of the casing through the channel 75.

The displacements, in the two directions, of the piston 62 are hence braked by a hydraulic resistance substantially proportional to the speed of displacement of the piston, whence there'arises a delay or damping effect.

The arrival of the regulating fluid under pressure is effected in the chamber 39a, through the passage 40a (FIG. 1). The chamber 39a is connected by pipes 77 and 78 (FIGS. 2 and 3) to a space 82 of an accumulator 79 (FIGS. 2 and 3) adapted to maintain the pressure of the fluid admitted through the pipe 40a at a substantially constant value.

As shown in FIG. 2, the accumulator 79 comprises two cylindrical chambers 80 and 81 which open into the common space 82. A piston 83 is displaced in each of thechambers against the action of elastic means 84. The tension of these elastic means 84 determines the value of the pressure at which the liquid admitted through the pipe 40a is maintained. If the pressure of the liquid has a tendency to increase, the piston 83 has a tendency to compress further the elastic means 84 and to uncover for this reason a lateral opening 85 which enables fluid to escape towards the zone A of relatively slight or nil pressure. A drop in the pressure of the fluid admitted through the pipe 40a is automatically caused.

The regulating fluid returns, through the exhaust pipe 44a (FIG. 2), to a reservoir (not shown) under atmospheric pressure. It is seen that the pipe 44a opens into the zone A of the casing and maintains the relative pressure of the fluid in this zone at nil.

Sealing means are of course provided to prevent any .escape of fluid from the casing. A diaphragm 86 (FIG.

1), in the form of a bellows, ensures, particularly, a fluidtight traversal of the wall of the casing by the rack 33a.

The operation of the regulating device 1a of FIGS. 1 to 4 will be explained by means of the diagrams of FIGS. 9 to 15.

The definition of statism for an engine will first be considered.

FIG. 8 shows three curves e, f and g showing the variations in the torque C of an engine, borne as ordinates, as a function of the speed of rotation N of the engine borne as abscissae.

The curve e shows the speed of the engine diminishes when the resistant torque (or the load) which is applied to it increases. In other words, if the speed of rotation of the engine is N when the resistant torque applied to the engine is nil, the speed of rotation N of the same engine, when the resistant torque which is applied to it is maximum, is less than N, the axial position of the cup 13a not being changed. The statism of the engine is defined in absolute value by the difference between the speed of rotation N, at nil load and the speed N at full load and, in relative value, by the ratio of the preceding difference to the speed of rotation of the engine at full load, that is to say by the ratio:

In the case of the curve 2, the statism is positive. It is immediately noted that the segment of the line f,

parallel to the axis of ordinates, corresponds to a nil.

statism and that the curve g corresponds to a negative statism.

There will now be studied the operation of the regulating device 1a in the case where the statism of this device is nil. FIGS. 9 to 13 correspond to this case.

It will be noted that by means of the threaded rod 55, the position of the pivot 53 is adjusted so that it occurs on the parallel to the axis of the rack 33a passing through the axis of the universal joint 12a.

Thus, the universal joint 12a, the finger 25a, the pin 59 and the pivot 53 occur exactly at the apices of a parallelogram. The axle 24a is situated at middistance from the universal joint 12a and from the finger 25a. The axle 58 is equidistant from the pin 59 and from the pivot 53 (FIG. 13).

When the speed is stable, that is to say when the engine operates at constant speed and at constant torque, the centrifugal force which acts on the weights 4a is constant and is balanced by the effect of the springs 10a, the axial position of the cup 13a not being modified by the sector 16a or by the drive reduction gear 49. The universal joint 12a is therefore immobile.

The differential piston 32a takes up a new equilibrium position for which the pressures of the regulating fluid, the chambers 39a and 38a, are respectively P and P/2. This is obtained, due to the by-pass cross-section which is established between the groove 50 of the pilot slide valve 22a and the differential piston 32a, the fluid escaping from the chamber 38a through the channel 30a to reach the zone A and to leave through the pipe 44a.

The differential piston 32a being in equilibrium and immobile. The lever 52 and hence the axle 58, are immobile. The same is the case for the axle 24a and hence for the lever 23a and for the pilot-slide valve 22a.

It is now assumed that the torque which the engine must overcome increases.

The flow per revolution of the injection pump not having increased, the torque supplied by the engine remains equal to that which was previously supplied, that is to say becomes less than the new resisting torque applied to this engine. For this reason, the rotary speed of the engine will have a tendency to diminish. This reduction in speed of v rotation of the engine is manifested by a reduction of the centrifugal force which acts on the weights 4a and hence by a displacement of the universal joint 12a towards the left. The universal joint takes up the position shown in interrupted line in FIG. 10.

In this FIG. 10, there has also been shown, in mixed lines, the position occupied by the lever 230 at the preceding state of equilibrium shown in FIG. 9.

This displacement of the universal joint 12a causes a rotation of the lever 23a around the axle 24a, immobile for the moment, in the clockwise direction. The slide valve 22a is displaced towards the right and the groove 50 is separated from the piston 32a. The by-pass crosssection between the groove 50 and the piston 32a increases (see FIGS. 9 and 10).

The pressure of the regulating fluid in the chamber 38a, which was equal to P/2, will diminish. Since the pressure of the fluid of the chamber 390 remains equal to P, the piston 32a will be displaced in the sense that is to say in the sense of an increase of flow and will drive the regulating rack 33a (FIG. 11).

It is assumed, obviously, that the new resisting torque that the engine must overcome is not greater than the maximum torque that the engine can supply at the rotary speed which has to be maintained constant.

This explanation makes it understandable that there will always be an increase of flow per revolution sufficient for the engine torque to become momentarily greater than the resisting torque and to cause an increase again in the speed of rotation, necessary to compensate the initial drop in speed.

It will be noted that the displacements of the differential piston 32a can be very rapid and that their speed is directly linked to that of the displacements of the slide valves 22a and, hence, to that of the displacements of the sleeve 9a. This speed depends on the speed of the variations of the resisting torque applied to the engine.

By being displaced in'the sense the piston 32a causes the rotation of the lever 52 around the pivot 53, in clockwise direction, as shown in FIG. 11, where the preceding position of the lever 52 is shown in mixed lines.

This rotation of the lever 52 causes a thrust, towards the right, of the rod 65 on the cup 66 through the shoulder 69. This thrust on the cup 66 is transmitted by the spring 68 to the cup 67 and to the compensating piston 62.

To explain the operation of the hydraulic time delay 61, there will first be considered two limiting cases, theoretical, corresponding respectively to very low and very high speeds of displacement of the piston 32a.

If the piston 32a is displaced very slowly as a result of a very slow variation of resisting torque, the axle 58 is displaced very slowly also. A simultaneous slow displacement, in the same direction, of the piston 62 will then be possible since the resistance opposed by the fluid aspirated into the channel 63a through the chamber 75 will be low, this resistance being substantially proportional to the speed of displacement of the compensating piston 62.

It may be said that the speeds of the compensating piston 62 and of the axle 58 are substantially equal when they are very low. In this case, the cup 67 remains constantly in abutment against the ring 70. A new state of equilibrium, shown in FIG. 12, is reached. This new state of equilibrium is explained in detail a little further on, by means of FIG. 13. If the piston 32 a is abruptly displaced as a result of an abrupt variation in the resisting torque, the speed of displacement of the axle 58 is very high.

The fluid which is aspirated into the chamber 63a, through the channel 75, opposing to the displacements of the piston 62 a resistance substantially proportional to the speed of the piston, will limit the speed to a value very much below that of the speed of the axle 58 and of the rod 65. In the limit, in the case where the displacements of the piston 32a will be instantaneous, the rod 65 would have finished its displacement before the piston 62 would have moved. The spring 68 would be further compressed and the ring 70 would be distinctly separated from the cup 67. The representation in FIG. 11 corresponds substantially to this limiting case. The lever 52 has already taken up its equilibrium position of FIG. 12 whilst the piston 62 continues to occupy the position that it had in FIGS. 9 and 10.

In practice, the situation is always between these two limiting cases, that is to say the compensating piston 62 starts to be displaced at the same time as the rod 65; as the abutment ring 70 is separated from the cup 67 and as the movement of the piston 62 ceases after that of the rod 65. At the same time as the differential piston 32a is displaced in the sense the speed of the engine increases as the universal joint 12a returns towards the equilibrium position that it occupied in FIG. 9.

To understand better what is the new equilibrium state of the device la obtained after a variation of the resisting torque, reference will be made to the very simplified diagram of FIG. 13.

The line D, represents the common geometrical axis of the rack 33a and of the slide valve 22a. The line D,, parallel to D,, represents the geometrical axis of the regulator 2. The distance between the lines D, and D, remains constant during the movements of the levers 23a and 52.

In the case of FIGS. 9 to 12, to which the diagram of FIG. 13 corresponds, the pivot 5.3 occurs, by adjust ment, on the line D, passing through the universal joint 12a.

By construction, the axle 25a and the pin 59 occur on the line D,. By construction also, the axles 24a and 58 occur on the line D,, parallel to the lines'D, and D,. In the case of the embodiment considered, D, is equidistant from D, and D When the regulating device 1a is in equilibrium, the pressure of the fluid in the chamber 38a is equal to P/2, which necessitates a well determined bypass cross-section between the groove 50 and the piston 32a. This fixed bypass cross-section defines a very specific relative position of the slide valve 22a and of the piston 32a. Finally, it may be said that the piston 32a is in equilibrium, when the distance between the finger 25a and the pin 59 is equal to a well determined value L.

By construction, the distance between the axles 24a and 58, when the cups 66 and '67 are in abutment respectively against the shoulder 69 and the ring 70, is equal to L.

In order that the regulating device should be in equilibrium, it is necessary that the cups 66 and 67 should be in abutment as has just been stated, so that the piston 62 is not subjected to any force.

The two conditions which must be satisfied in order that the regulating device la should be in equilibrium are hence as follows:

the distance between the finger 25a and the pin 59 must be equal to L; the distance between the axle 24a and the axle must be equal to L.

In FIG. 13, a first equilibrium position of the axles 25a, 24a, 58, of the pin59and of the universal joint 12a has been shown in continuous lines. For this equilibrium position, the flow per revolution of the injection pump, fixed for the position of the pin 59 on the line D,, is such that the engine torque is equal to the resisting torque and that the rotary speed remains constant. The distances between, on one hand, the finger 25a and the pin 59 and, on the other hand, the axles 24a and 58, are equal to L.

For a higher resisting torque, the new state of equilibrium is such that the pin 59 occupies the position shown in mixed lines, for which the flow per revolution of the pump is greater than the preceding value so as to ensure an engine torque equal to the resisting torque. This new state of equilibrium, as explained previously, is such that the distance between the finger 25a and the pin 59 are equal to L in order that the piston 32a (FIG. 12) should be in equilibrium.

The position of the-finger 25a on the line D, is hence completely fixed from the position of the pin 59.

The equilibrium state is again such, as previously explained, that the distance between the axles 58 and 24a is equal to L. The position of the axle 58 is fully determined since it occurs at the intersection of the line joining the pivot 53 to the pin 59 and of the line D The position of the axle 244 on the line D is, also, completely determined, at equilibrium, since the distance of the axle 24a to the axle 58 is equal to L.

The new equilibrium positions of the finger 25a and of the axle 24a being fully determined, the new equilibrium position of the universal joint 12a occurs at the intersection of the line passing through the finger 25a and the axle 24a and of the line D,.

It is seen from FIG. 13 that the geometry of the device is such that this intersection is a fixed point of the line D, situated at the distance L from the pivot 53.

- Whatever the torque required from the engine, the rotary speed of the latter, un der stable conditions, will be constant since the position of equilibrium of the universal joint 12a is fixed. The statism is hence nil.

From FIG. 13, it is immediately seen that the universal joint 12a occupies a fixed equilibrium position because the pivot 53 occurs on the parallel D, to the line D, passing through the said universal joint.

If now, by acting on the threaded rod 55, the pivot 53 is displaced in a direction perpendicular to D,, it is understood that the line passing through the finger 25a and the axle 24a will occupy successive equilibrium positions which will all pass through a fixed point situated on the parallel to D, passing through the pivot 53. This fixed point will be situated at the distance L from the pivot 53. It will also be understood that in this case the equilibrium positions of the universal joint 12a on the parallel D will be situated at distances from the pivot 53 different from L.

In particular, if the pivot 53 is arranged in such a way that the distance of this pivot to the line D is less than the distance of the universal joint 12a to the same line, the diagrammatic configuration of FIG. 14 is obtained.

.In this case, the various equilibrium positions possible for the longitudinal geometrical axis of the lever 23a all pass through a fixed point 87 derived from the pivot 53 by a translation parallel to D, and of amplitude L. This point 87 is situated between the universal joint 12a and the ringer 25a. It will be immediately apparent that, on passing from the equilibrium position of the lever 230, shown in mixed lines, to the equilibrium position shown in full lines, the flow per revolution, at equilibrium, increases whilst the rotational speed, at equilibrium, diminishes. In other words, when the engine torque increases, the speed diminishes: the statism is positive.

To obtain a negative statism, that is to say an operational speed of the engine unloaded, N smaller than the fully loaded speed of the engine N (curve g, FIG. 8), it suffices to adjust, by means of the threaded rod 55, as shown in FIG. 15, the position of the pivot 53 so that the distance of this pivot to the line D, is greater than the distance from the universal joint 12a to this same line. In this case, the various equilibrium positions of the longitudinal geometrical axis of the lever 23a all pass through a fixed point 88 derived from the pivot 53 by a translation parallel to D, and of amplitude L. The universal joint 12a occurs between this point 88 and the finger 25a.

It will be immediately apparent, according to FIGS. l3, l4 and 15, that the line D,, on which the axles 58 and 24a occur, does not need to be equidistant from the lines D, and D,. It suffices that this line D, be parallel to the lines D, and D, in order that the operation of the device remains identical with that which has just been described.

Referring to FIG. 5, there can be seen a regulating device la equipped with a flow stop 29b in the form of a rod. This stop plays a similar role to that of the stop 29a of FIG. 1. The position of this stop 29b along the direction of the axis of the flow adjustment rack can be modified by means of an eccentric 89 turning around an axle 90 at right angles to the average direction of the stop 29b and actuated by a lever 91. Elastic return means 92 are provided to hold the stop 29b supported against the eccentric 89. The position of the stop can be adjusted during the operation of the engine.

In FIG. 6, there is shown another variation of the flow stop. The latter, denoted by 29c, comprises a pusher 99 supported against the pilot slide valve 22a and linked in translation to the plunger core 93 of an electromagnet 94. A set of shims 95 enables the travel of the plunger core 93 to be adjusted and this by means of the pusher 99. An externally threaded sleeve 96, rigidly fixed to the electromagnet 94, is screwed in the wall of the casing of the regulating device 1a and enables adjustment of the longitudinal position of the pusher 99 and, hence, to set a maximum value to the flow per revolution. A lock-nut 97 is provided to immobilize the threaded sleeve 96 after adjustment. According as the electromagnet 94 is energized or not, the plunger core 93 comes into contact with a fixed core 98 or remains separated from it, as shown in FIG. 6. For a given adjustment of the threaded sleeve 96, two maximum values of the flow per revolution can hence be set according as the electromagnet 94 is or is not enei' gized.

In FIG. 7, there is shown a variation 'of the device for arrest of injection.

.In FIG. 1, the actuation of the arrest of the injection is effected by means of a finger 28a which acts directly on the pilot slide valve 22a.

The device for arrest of injection of FIG. 7 enables the pipe 44a to be covered ensuring the return of the regulating fluid to the reservoir under atmospheric pressure.

For this purpose, a slide valve 102 actuates the opening or closing of the pipe 44a. The displacements of the slide valve 102 are actuated by an electromagnet similar to that of FIG. 6 and denoted by the same reference number 94. The slide valve 102 is linked in translation to the plunger core 93 of the said electromagnet and can occupy respectively a closed position and an open position, according as the electromagnet 94 is or is not energized. If the electromagnet 94 is energized, the plunger core 93 comes into contact with the fixed core 98 and the slide valve 102 actuates the opening of the return pipe 44a which then communicates with the zone A of the casing of the device 10. This zone is under relatively low or nil pressure and the device operates as previously explained.

When the electromagnet 94 is not supplied with current, elastic means 100 separate the plunger core 93 from the fixed core 98, the said plunger core being supported against a stop 101 (position shown in FIG. 7). In this position, the return pipe 44a is closed.

The pressure of the fluid in the zone A of the casing will increase and it will be the same for the fluid situated in the chamber 38a (see FIG. 1). The differential piston 32a will hence be displaced in the sense actuating a reduction in flow per revolution. The displacement of the differential piston 32a continues until cessation of the flow since, any flow from the chamber 38a towards the zone A having ceased as a result of the closing of the pipe 44a, the pressure in the. chamber 38a has a tendency to become equal to P, which pressure exists in the chamber 39a, of cross-section less than that of the chamber 38a.

Whatever the embodiment adopted, there is obtained a regulating device for the flow per revolution for an injection pump which is of simple construction, of small bulk and of which the number of parts is relatively reduced, which enables a low cost price to be achieved. The operation of the regulating device according to the invention is insensitive to the nature, to the temperature, and to the variations in pressure and flow of the regulating fluid. For this reason, the regulating fluid can be constituted either by a hydraulic oil, or by the oil serving for the lubrication of the engine.

There can also be utilized as a regulating fluid the fuel of the engine, in which case the hydraulic source of the regulating fluid is advantageously constituted by the fuel pump of the engine. In fact, although the pressure of the fluid delivered by the fuel pump is generally low, it is still sufficient to ensure correct operation of the regulating device according to the invention, for which the pressure P, in the chamber 39a, can be (in relative value) of the order of 200 millibarsl In addition, with such a device, the differential piston 32a, which actuates the displacements of the rack 33a, oscillates continually, which favors a good positioning of this piston and the maintenance of good lubrication of the walls of this piston in contact with the bore of the cylinder 34a. The inertia of the servo device is thus reduced. 7

The statism of the engine can be adjusted at will and this in a very simple manner, by adjusting the knob 56 controlling the threaded rod 55.

All the other auxiliary devices which are generally encountered in conventional regulating devices are conserved, especially regulation of the flow at full load, the adjustment of supercharging on starting, the actuating of the arrest of injection at a distance, etc.

The regulating device can be incorporated in the injection pump as shown in the drawings, but can also be independent.

Such a device can advantageously be used on an internal combustion engine forming part of an electrogenerator plant. In fact, for the production of alternating electric current, it is particularly advantageous to provide an internal combustion engine of which the statism is very low, preferably nil, so that the frequency of the alternating current remains substantially constant whatever the load.

A regulating device for the flow per revolution for an injection pump according to the invention has also all the advantages possessed by devices using a hydraulic servo system, that is to say a substantial actuating force for the regulating member for the flow can be obtained without it being necessary to provide a regulator, 2a of which the weights, 4a are substantial.

As is self-evident, and as emerges already from the preceding description, the invention is in no way limited to those of its methods of application, not to those of its methods of production of its various parts, which have been more especially indicated; it em-' braces, on the contrary, all variations.

1 claim:

1. Device for regulating the flow of fuel per revolution for the injection pump of an internal combustion engine which comprises:

a centrifugal regulator adapted to be driven by the engine;

a first element actuated by the centrifugal regulator through a lever,

and a second element actuating :a regulating member for the flow per revolution of the pump to which it is mechanically linked, said elements being adapted to be displaced along; parallel or common axes;

actuating means for the displacements of the second element, from those of the first element, comprising an hydraulic servo device using a fluid under pressure;

regulating means enabling variations in the speed of rotation of the engine to be adjusted as a function of the load on the engine, comprising a second lever parallel to the first said lever, adapted to act on the servo device according to the displacements of the regulating member of the flow per revolution,

said hydraulic servo device being of the follower type and comprising a pilot slide valve constituting said first element and a differential piston constituting said second element, said slide valve and differential piston being adapted! to define a variable size by-pass depending on their relative position and to establish a loss which actuates the displacements of said differential piston and hence of the regulating member of the flow per revolution, and

said first lever and the second lever being respectively articulated in their middle portion on an axle adapted to be displaced in a direction parallel to the axes of said pilot slide valve and differential piston, a hydraulic time-delay connecting the axles of the two levers to one another, the first lever being linked, at each of its ends, respectively, to the pilot slide valve and to an active member of the centrifugal regulator adapted to slide along the axis of the latter, the second lever being articulated, at one end, on a pivot fixed in the direction of the axis of said slide valve but adjustable in a direction at right angles to the axis of said slide valve and, at its other end, being articulated on the regulating member for the flow per revolution of the pump. a

2. Device for regulating the flow of fuel per revolution for an injection pump of an internal combustion engine which comprises:

a centrifugal regulator adapted to be driven by the engine, comprising an active member adapted to slide along the axis of the centrifugal regulator, under the effect of a force depending on the speed of rotation of the engine,

a regulating member for the flow per revolution of the pump,

a hydraulic servo device of the follower type, adapted to actuate displacements of the regulating member of the flow per revolution from displacements of said active member of the centrifugal regulator, said follower servo device comprising a pilot slide valve mechanically linked to the active member of the centrifugal regulator, and

a differential piston, mechanically linked to the regulating member of the flow per revolution, said differential piston having two external diameters and sliding in a cylinder to define two chambers of different cross-sectional areas, a passage being provided communicating said two chambers permanently with one another, the pilot slide valve and the differential piston being adapted to define between them a variable size bypass depending on their relative positions and to establish a load loss which actuates continual oscillating displacements of said differential piston,

said pilot slide valve being adapted to slide in a bore provided in the differential piston and to be guided by the latter, and including a longitudinal channel opening inside said bore through at least one lateral port which cooperates with the surface of said bore of the differential piston to define said variable size by-pass.

3. Regulating device according to claim 1, wherein the hydraulic delay comprises a compensating piston adapted to slide in the bore of a cylinder, the compensating piston being rigidly fixed, on one side, to the axle of the first lever and including a bore opening towards the second lever, the median axis of rotation of said second lever being borne by a rod coaxial with the piston and extending into the bore of said piston by a portion bearing two cups between which a spring is compressed, said cups being adapted to co-operate, when the hydraulic delay is inactive, with a shoulder and a stop ring provided in the bore of the compensator piston and, when the hydraulic delay is in action, with a stop ring or a shoulder provided on the rod.

4. Regulating device according to claim 3, arranged so that the median axes of the levers are situated on a line parallel to the axle of the regulating member for the flow per revolution and to the line passing through the linking elements of the levers respectively with the pilot slide valve and the flow regulating member.

5. Regulating device according to claim 4, arranged so that the median axes of the levers and the linking elements are situated at equilibrium condition of the device, at the apices of a parallelogram.

6. Regulating device according to claim 1, wherein the articulating pivot of the second lever is rigidly fixed to a nut mounted on a threaded rod with axis at right angles to the axis of rotation of the second lever and to the axis of the pilot slide valve, the threaded rod including, at one end, a rotary control knob, accessible from the outside of the regulating device, said pivot cooperating with a longitudinal slot provided in the lever and the nut comprising a lug adapted to cooperate with a groove provided on the casing to prevent said nut from turning so that on rotation of the threaded rod, the nut is moved along said rod.

7, Regulating device according to claim 1, wherein the articulating pivot of the second lever is rigidly fixed to a nut mounted on a threaded rod with axes at right angles to the axes of rotation of the second lever and to the axis of the pilot slide valve, the threaded ro d includ mg, at one en a rotary control knob, accessible from the outside of the regulating device, said pivot cooperating with a longitudinal slot provided in the lever and the nut comprising a lug adapted to co-operate with a groove provided on the casing to prevent the said nut from turning so that on rotation of the threaded rod, the nut is moved along said rod.

8. Regulating device according to claim 2, wherein the differential piston is adapted to be displaced in a cylinder closed at its end remote from the control member of the flow per revolution by a cap having an aperture traversed in fluid-tight manner by the pilot slide valve, said cap being displaceable in translation in a plane at right angles to the axis of the pilot slide valve.

9. Regulating device according to claim 2, wherein the end of a lever is connected to the pilot slide valve and includes a finger equipped with a roller, adapted to abut against the slide valve in one direction which corresponds to a reduction of the flow per revolution, said finger being connected to the pilot slide valve by elastic means, housed in the longitudinal channel and adapted to hold the roller against the slide valve.

10. Regulating device according to. claim 1, including a hydraulic accumulator, adapted to hold the supply pressure of the servo device constant.

1 l. Regulating device according to claim 1, including a slide valve, controlled by an electromagnet, adapted to close the pipe for the return of the regulating fluid to atmospheric pressure so that, when said pipe is closed, the differential piston actuates the cessation of the flow per revolution and the arrest of the engine.

12. Regulating device according to claim 1, including a stop for the flow per revolution actuated by an electromagnet.

13. Regulating device according to claim 1, including a stop for the flow per revolution actuated by an eccentric. 

1. Device for regulating the flow of fuel per revolution for the injection pump of an internal combustion engine which comprises: a centrifugal regulator adapted to be driven by the engine; a first element actuated by the centrifugal regulator through a lever, and a second element actuating a regulating member for the flow per revolution of the pump to which it is mechanically linked, said elements being adapted to be displaced along parallel or common axes; actuating means for the displacements of the second element, from those of the first element, comprising an hydraulic servo device using a fluid under pressure; regulating means enabling variations in the speed of rotation of the engine to be adjusted as a function of the load on the engine, comprising a second lever parallel to the first said lever, adapted to act on the servo device according to the displacements of the regulating member of the flow per revolutioN, said hydraulic servo device being of the follower type and comprising a pilot slide valve constituting said first element and a differential piston constituting said second element, said slide valve and differential piston being adapted to define a variable size by-pass depending on their relative position and to establish a loss which actuates the displacements of said differential piston and hence of the regulating member of the flow per revolution, and said first lever and the second lever being respectively articulated in their middle portion on an axle adapted to be displaced in a direction parallel to the axes of said pilot slide valve and differential piston, a hydraulic time-delay connecting the axles of the two levers to one another, the first lever being linked, at each of its ends, respectively, to the pilot slide valve and to an active member of the centrifugal regulator adapted to slide along the axis of the latter, the second lever being articulated, at one end, on a pivot fixed in the direction of the axis of said slide valve but adjustable in a direction at right angles to the axis of said slide valve and, at its other end, being articulated on the regulating member for the flow per revolution of the pump.
 2. Device for regulating the flow of fuel per revolution for an injection pump of an internal combustion engine which comprises: a centrifugal regulator adapted to be driven by the engine, comprising an active member adapted to slide along the axis of the centrifugal regulator, under the effect of a force depending on the speed of rotation of the engine, a regulating member for the flow per revolution of the pump, a hydraulic servo device of the follower type, adapted to actuate displacements of the regulating member of the flow per revolution from displacements of said active member of the centrifugal regulator, said follower servo device comprising a pilot slide valve mechanically linked to the active member of the centrifugal regulator, and a differential piston, mechanically linked to the regulating member of the flow per revolution, said differential piston having two external diameters and sliding in a cylinder to define two chambers of different cross-sectional areas, a passage being provided communicating said two chambers permanently with one another, the pilot slide valve and the differential piston being adapted to define between them a variable size bypass depending on their relative positions and to establish a load loss which actuates continual oscillating displacements of said differential piston, said pilot slide valve being adapted to slide in a bore provided in the differential piston and to be guided by the latter, and including a longitudinal channel opening inside said bore through at least one lateral port which cooperates with the surface of said bore of the differential piston to define said variable size by-pass.
 3. Regulating device according to claim 1, wherein the hydraulic delay comprises a compensating piston adapted to slide in the bore of a cylinder, the compensating piston being rigidly fixed, on one side, to the axle of the first lever and including a bore opening towards the second lever, the median axis of rotation of said second lever being borne by a rod coaxial with the piston and extending into the bore of said piston by a portion bearing two cups between which a spring is compressed, said cups being adapted to co-operate, when the hydraulic delay is inactive, with a shoulder and a stop ring provided in the bore of the compensator piston and, when the hydraulic delay is in action, with a stop ring or a shoulder provided on the rod.
 4. Regulating device according to claim 3, arranged so that the median axes of the levers are situated on a line parallel to the axle of the regulating member for the flow per revolution and to the line passing through the linking elements of the levers respectively with the pilot slide valve and the flow regulating member.
 5. RegulatinG device according to claim 4, arranged so that the median axes of the levers and the linking elements are situated at equilibrium condition of the device, at the apices of a parallelogram.
 6. Regulating device according to claim 1, wherein the articulating pivot of the second lever is rigidly fixed to a nut mounted on a threaded rod with axis at right angles to the axis of rotation of the second lever and to the axis of the pilot slide valve, the threaded rod including, at one end, a rotary control knob, accessible from the outside of the regulating device, said pivot co-operating with a longitudinal slot provided in the lever and the nut comprising a lug adapted to cooperate with a groove provided on the casing to prevent said nut from turning so that on rotation of the threaded rod, the nut is moved along said rod.
 7. Regulating device according to claim 1, wherein the articulating pivot of the second lever is rigidly fixed to a nut mounted on a threaded rod with axes at right angles to the axes of rotation of the second lever and to the axis of the pilot slide valve, the threaded rod including, at one end, a rotary control knob, accessible from the outside of the regulating device, said pivot co-operating with a longitudinal slot provided in the lever and the nut comprising a lug adapted to co-operate with a groove provided on the casing to prevent the said nut from turning so that on rotation of the threaded rod, the nut is moved along said rod.
 8. Regulating device according to claim 2, wherein the differential piston is adapted to be displaced in a cylinder closed at its end remote from the control member of the flow per revolution by a cap having an aperture traversed in fluid-tight manner by the pilot slide valve, said cap being displaceable in translation in a plane at right angles to the axis of the pilot slide valve.
 9. Regulating device according to claim 2, wherein the end of a lever is connected to the pilot slide valve and includes a finger equipped with a roller, adapted to abut against the slide valve in one direction which corresponds to a reduction of the flow per revolution, said finger being connected to the pilot slide valve by elastic means, housed in the longitudinal channel and adapted to hold the roller against the slide valve.
 10. Regulating device according to claim 1, including a hydraulic accumulator, adapted to hold the supply pressure of the servo device constant.
 11. Regulating device according to claim 1, including a slide valve, controlled by an electromagnet, adapted to close the pipe for the return of the regulating fluid to atmospheric pressure so that, when said pipe is closed, the differential piston actuates the cessation of the flow per revolution and the arrest of the engine.
 12. Regulating device according to claim 1, including a stop for the flow per revolution actuated by an electromagnet.
 13. Regulating device according to claim 1, including a stop for the flow per revolution actuated by an eccentric. 